sbt多模块项目：项目之间的依赖

Question

I am new to Scala, so I hope this question is not too naive.

Suppose I have a multi-module sbt-project and there is a dependence between projects.

  lazy val core = (project in file("core")).
    settings( ... )

  lazy val utils = (project in file("utils")).
    settings( ... ).dependsOn(core)

The question, does .dependsOn(core) mean that if I do projects utils; compile projects utils; compile it is going to compile the core beforehand (and use its latest version)?

I am asking this, since in practice I don't see this behavior (and I want it).

Answer 1

You are looking for the aggregate method. Like this:

lazy val utils = (project in file("utils")).
  settings( ... ).dependsOn(core).aggregate(core)

The aggregate method here causes all tasks run on utils to also be run on core (update, etc...). If you want to disable a task from running on an aggregated project you can check out the documentation here

Answer 2

Yes, you should see this behavior (and I do see it in practice). As the linked documentation says (note that the roles of util and core are opposite there: core depends on util ):

This also creates an ordering between the projects when compiling them; util must be updated and compiled before core can be compiled